Preparation of di-grignard organometallic derivatives



PREPARATION OF DI-GRIGNARD ORGANO- METALLIC DERIVATIVES .18 Claims. (Cl. 260-665) This invention relates generally to a novel method for the preparation of bis-halomagnesio compounds and,

more particularly, to the production ofaliphatic unsatu-- rated di-Grignard reagents by thedirn'erization of selected olefinic reactants in the presence of an alk-ali metal and a solid, anhydrous, reactive magnesium :hal'ide. Specificaily, the process relates to improvements wherein unsaturated hydrocarbons such as aliphatic conjugated diolefins undergo dimen'zation and reaction in the presence of finely divided sodium metal and a magnesium halide to give di-halomagnesium derivatives of the dimers.

It is known to carry out various types of reactions in which organo-sodium compounds are prepared. One particularly valuable class of sodium derivatives which can readily be made from olefins, preferably those of; the conjugated aliphatic diolefinclass, is obtained by reacting nite tates Patent.

them under selective conditions with metallic sodium. 1

Under suitable conditions, the sodiumaddition products first formed dimerize by coupling to provide a practical synthesis for desirable aliphatic hydrocarbon'structures. Thus, the selective reaction of diolefins, such as butadiene, dimethylbutadiene, isoprene, and the'methyl pentadienes with elemental sodium gives dimeriz'ed disodium derivatives.

commercial method for convertingdimerized olefin derivatives into bis-halomagnesio compounds; 'lTlies di- Grignard reagents can befurther reacted to yield highly valuable, related products.

Another object of the invention is to effectively convert olefinic reactants in one step to the desired di- Gri'gnardreagents in' high yields-and selectivity.-' These reagents can be further converted toothervalhable derivatives since they readily undergo-all typical-reactions of Grignard compounds;

A specific object of this inventionis toprovide a novel and practical method for making bis-halomagnesiooctadienes directly from butadiene, sodium, and anhydrous magnesium chloride, at the same time employing the-magnesium'chloride as a solidattrition agent in the initial re"- action bet-weenbutadiene and metallic sodium.

Other objects will become apparent from the complete description of the invention which is setforthbelow.

It is'further also known that in carrying out the selective dimerization reaction of the diolefinic reactants such as butadiene with metallic sodium a remarkable and unexpected increase in reaction rate and, in effect, an overall increase in: the speed of the reaction, can be achieved by the use of a solid friable attrition agent. The use of these agents has been found to give increased utilization of the sodium. That is, the use of an appropriately sized attrition agent and, preferably, one which is capable of undergoing pulverization under the conditions-v of the reaction, hasbeen' found to efiect. a'rsubstantial rise in yield ofdimerization products based" on the sodium utilized and,. at the same time,-such use maintyields based on the olefin.

2,795,,6125 lCe Pa ented Ju 195.7

solid magnesium halide, preferably magnesium chloride.

The products of-the initial reaction between the unsaturated reactants and the alkali metal are the dimetallo-dienes but the final products are the di-halomagnesio-dienes. Presumably, the alkali metal organic compounds react as rapidly as formed with the magnesium halide present in the reaction mixture although the precise mechanism-is not known. Thesenew bis-halomagnesiodienejs 'undergo all" the typical reactions of this typeof compounds suchas reaction with carbon dioxide to give dibasic acids, reactions with oxidizing agentsepoxides, or carbonyl compoundsto give glycols, reactions withsulfur dioxide to give di-sulfinic acids, and the like;

The d-iolefins which can be used for this improved process incIude any aliphatic conjugated diolefins, for example'; buta'diene, isoprene, dimethylbutadiene, the pentadi- "cues, such as the methyl-l,3 pentadienes, and thellike.

wherein R, RT'an dR", represent either hydrogen or alkyl radicals, R'" representsan alkenyl radical, and m' and 21 represent whole number integers of from 0 to 1, inclusive. .It is necessary that the alkali metal. tobe used should be initially in .a'finely divided form. In generaL-this re- .g'u'ires' that the sodium be in a finely dispersed state ina'liquid reaction-medium. Althougheither sodiurn or potassiummay be used as the alkali metal reactant," the use of-sodi-um is much preferred over potassium since sodium gives excellent selectivities and yields of dimerized products, and it is cheaper and more readily available. Mixturesof sodium and potassium, and of sodium and calcium can alsobe used. 1

A sodium dispersion in which the average particle size is less than 50 microns is quite satisfactory for carrying out theprocess, the prefer-red size range being 1 to l0 microns. This dispersionis most conveniently made in an inert hydrocarbon medium as anrinitial step preliminary to the react-ion with the'di'ene compound;

The reaction medium found most suitable for use consists essentially of an ether and only certain types of ethers are effective. These particular classes of ethers appear" to have the common property of serving as promoters- -of-- -the' selective dimeri'zation reaction involved. The ether can: be any aliphat-icmono ether having a methoxy groupyin which the ratio-ofthe number of oxygen atoms to. the number of carbon atoms is not less than 1:4. Examples include dimethyl ether, methyl ethyl ether, methyl n-propyl ether, methyl isopropyl ether, and mixtures of these methyl ethers. Certain aliphatic polyethers. arealso quite'sa'tisfactory. These include the acyclic and cyclic polyethers which are-derivedby re? placing all of the hydroxyl hydrogen atoms of the apt The ether should not contain any groups'such as hydroxyl, carboxyl, and the like which are distinctlyreactive towards sodium. Although the ether may react in some reversible manner, it must not be subject to extensive cleavage. Such cleavage action destroys the ether, uses up sodium and introduces into the reacting system sodium alkoxides. These alkoxides in turn'tend to induce the rubber forming reactions'with the unsaturated reactant rather than the desired dimerization reac tion.

Although the reaction medium shouldconsist essentially of the specified ethers, other inert media can be present in limited amounts. In general, these inert media will be introduced with the sodium dispersion as the liquid in which the sodium is suspended and will act chiefly as 'diluents. The concentration of ether in the reaction mixture should at all times be maintained at a sufiicient level to have a substantial promoting effect upon the desired dimerization reaction.

It is usually desirable to include in the dimerization reaction mixture at least one supplementary activating material. This material is a relatively small amount of at least one material from the class of polycyclic aromatic compounds. By this term it is intended to include both condensed ring hydrocarbons such as naphthalene and phenanthrene, as well as the uncondensed polycyclic compounds such as diphenyl and the terphenyls and their mixtures which have also been found to be particularly useful. The amount of the hydrocarbon to be used will vary over a range which in every case will be relatively small in comparison with the amount of diolefin or vinyl aromatic compound undergoing reaction. Concentrations in the range of 0.1 to wt. percent based on the amount of diolefin are ordinarily quite suiiicient.

The magnesium halide preferred for use is anhydrous magnesium chloride, since it is relatively more stable,

readily obtainable and available at low cost. It is especially necessary that it be employed in an anhydrous state. The anhydrous salt can be added to a pebble mill or ball mill or other type attrition reactor in contact with the solid dispersed metallic sodiumand the reaction medium wherein the salt is simultaneously ground down to an etfective particle size. Or, the mag nesium salt can be preground before introduction to the mill and/or before introducing sodium and other reaetants. The former method is to be preferred in larger scale industrial operations since the reaction-of the so dium with the conjugated diolefin can be initiated'substanti ally simultaneously with the start of the grinding action.

Amounts of the magnesium salt equivalent to at least one mole per mole of the original olefinic reactant used are necessary and, generally, quite satisfactory. Somewhat larger amounts are effective to obtain good results for using the salt as an attrition agent throughout the entire reaction period. t

It is a further requirement in the process that the reaction temperature throughout the entire process preferably be held between 4() C. and +40". The temperature range between 0 and 40 C. isthe preferred one. cleavage products at temperatures of about 0 C. and above with the result that suificient alkoxides are formed to yield unwanted by-products rather than the required dimers.

A typical reaction using the process of the invention is carried out by placing an inert hydrocarbon such as isooctane in a suitable vessel with the appropriate amount Generally speaking, all ethers begin to yield 1 I V v 7,.

of sodium metal. The mixture is heated in surrounding bath or otherwise until the sodium has melted (M. P. 97.5 G). Then a suitable high speed agitator is started and, preferably, an emulsifier consisting, for example, of /2 (based on sodium) of the dimer of linoleic acid, is added. After a short period of agitation a test sample of the dispersion shows the particle size to be in the 5-15 micron range.

g The stirring is stopped and the dispersion is allowed to cool to room temperature. This dispersion is now ready to be used in the preparation of the di-Grignard type compounds. Inert liquids such as saturated dibutyl ether normal octane, n-heptane, or straight run kerosenes, may be employed as suspension media for the dispersion. Any such dispersion having sufficiently finely divided sodium will sufiice. Other Well-known substances may be used instead of the dimeric linoleic acid as the dispersing agents. This sodium dispersion is preferably added to a selected ether which is precooled to and maintained between 0 C. and 40 C. It is only necessary to employ an amount of dispersed sodium stoichiometrically equal to the appropriate olefinic reactant to be initially dimerized. The solid magnesium chloride is also added to the mixture. The diolefin reactant compound is preferably introduced slowly. One method is to introduce this reactant into the reaction vessel at approximately the same rate as that at which it reacts with the metallic sodium and magnesium chloride. It is highly desirable to maintain constant agitation within the reaction mixture. In order to take advantage of the maximum eifect of the presence of the solid magnesium halide, the most elfective agitation is to be achieved by conducting the reaction in a ball mill, pebble mill or similar mill suitable for wet grinding.

. The separation of the products can be made by relatively simple and well-known chemical means. The di- Grignard derivatives can either be isolated as such, or they can be directly and immediately thereafter used as chemical intermediates and subjected to further reactions to form valuable derivatives. For instance, subsequent carbonation of the mixture containing these products yields the salts of dicarboxylic acids. The carbonation may be done by subjecting the di-Grignard derivatives to dry gaseous carbon dioxide, by contact with solid carbon dioxide or by means of a solution of carbon dioxide.

.ofifers advantages over the necessary low-temperature carbonation of certain other types of metallo organic compounds. The carbonation forms the dimetallic salts of the unsaturated aliphatic dicarboxylic acids. These salts contain two more carbon atoms than the dimetallic diene dimers from which they are produced.

Where butadiene is the starting aliphatic diolefiu and sodium is employed without magnesium chloride as an additional reactant, there results on carbonation the selective production of C-IO unsaturated dicarboxylic acids, comprising an isomeric mixture of 3,7-decadiene-1, 10- dioic acid, 1,7-decadiene-3, 6-dioic acid and 1,6-decadiene- 3,10-dioic acid in the ratio of 3.5/ 1/5. The present invention is of particular importance in that the carbonation of the products of the di-Grignard type yields a mixture of dibasic C-lO unsaturated acids containingsubstantially less straight chain molecules. Thus, the ratio of 3,7-decadiene-l,l0-dioic acid, l,7 decodiene-3,6-dioic acid and .l,6-decadiene-3,l0-dioic acid is 2.5/3/4. The larger amount of the 1,7-decadiene-3,6-di0ic acid (2,5-divinyladipic acid) is especially importantsince this'acid is the most valuable in the preparation of drying oils and alkyd resins. e

The Grignard groupings formed undergo all typical reactions common to .these compounds. They undergo reaction with carbonyl compounds such as aldehydes and ketones to form glycols. They also react with epoxides to give glycols. Many other reactionsv are well known .glycols vand'with chloramine to give diamines.

, The unsaturated products resulting directly therefrom .find'use as chemical intermediates, and are valuable in the preparation of drying oils, polymers, copolymers, and plasticizers. The resultant diacidandglycol derivatives are useful in the formation of esters, polyesters, polyamides and generally as chemical intermediates.

The unsaturated derivatives can be hydrogenated at the double bonds to yield .the corresponding saturated compounds, particularly the saturateddiacids and saturated glycols. For example, the di-Grignard product obtained from butadiene ultimately yields after carbonation and hydrogenation a practically quantitative mixture of sebacic, Z-ethylsuberic, and -2,--diethyladipic acids. It is of especial value tonote that when operating in this manner and by this process, a much larger proportion of 2,5-diethyladipic acid is obtained in the final mixture than when the isomeric-mixture isobtained via other routes.

The presence of the-carbon to magnesium bond is demonstrated by the analogous reactions of phenylsodium and phenylmagnesiumchloride from which the-products are well-known and easily identified. When phenylsodium'is prepared in toluene and the reaction mixture refluxed for two hours after the formation of the phenylsodium is complete, benzylsodium is formed quantitatively. Carbonation gives only phenylacetic acid. If carbonation is efiected before the reflux period, only benzoic acid is obtained. It is known that 'Grignard reagents will not effect metalation reactions and thus phenylmagnesium chloride will not metalate toluene to give benzylmagnesium chloride. Accordingly, when chlorobenzene was added to a mixture of metallic sodium and magnesium chloride in toluene, phenylmagnesium chloride was formed. The reaction mixture was refluxed for two hours and carbonated by pouring over solid carbon dioxide. Only benzoic acid was obtained whereas if benzylsodium were present by a metalation reaction between phenylsodium and toluene, phenylacetic acid would have resulted. Thus, it was shown that the phenylsodium reacted with the magnesium chloride as rapidly as formed to give phenylmagnesium chloride.

In a similar manner, it can be shown that, during the process described herein, there is a carbon to magnesium bond formed resulting in the Grignard type grouping, and producing thereby the di-Grignard derivatives. Thus, it was shown that disodiooctadiene would metalate triphenylmethane to give triphenylmethylsodium which on carbonation gives triphenylacetic acid. When magnesium chloride Was present and the di-Grignard reagent formed, no metalation of the triphenylmethane could be noted.

The invention will be described in greater detail by the following examples. These examples and embodiments are illustrative only and the invention is not in any way intended to be limited thereto except as indicated by the appended claims. All parts are expressed by weight unless otherwise specified.

Example 1 Disodiooctadiene was prepared by adding 112 parts (2.0 moles) butadiene to 46 parts (2.0 g. atoms) of dispersed sodium in 500 parts dimethyl ether solvent containing 2 parts of oterphenyl at -30 C.; the estimated yield of disodiooctadiene from the reaction was 0.75 mole. Carbonation of the reaction mixture on solid carbon dioxide followed by acidification and hydrogenation gave 75% yield of a mixture of carbon atom dibasic acids. The composition of this mixture consisted of essentially 38 parts of sebacic acid, 50 parts of a-ethylsuberic acid and 12 parts of a,a'-diethyladipic acid.

Example 2 To a mixture of 46 parts (2.0 g. atoms) of sodium (2. 50% dispersion in isooctane) and 190 parts of anhydrous magnesium chloride and v1500 parts of dimethyl ether containing'4 partsiof o-terphenyl carrier ata temperature of 23 C., was added over a period of one hour, 108 partsf(2;0 moles) of .butadiene. Carbonation of the resulting bis-chloromagnesio octadiene on solid carbon dioxidefollowed by hydrogenationand acidification gavea 60% yield ofa mixture of dibasic acids. The mixture of acids consisted of'28 parts sebacic acid, 42 parts of u-ethylsubericacid and 30 parts of a,oc' diethyladipic acid.

Example v3 Disodiooctadiene wasprepare'd by adding 112 parts ,of butadiene to 46 parts of sodiumdispersed in 500 parts of dimethyl et-her solvent containing 2 parts of o-terphenyl at -30 C. the estimated yield of disodiooctadiene from the reaction was 0.75.,mole. Color Test I (ref. 1, 'Gilman and'Schulze, J. Am. ChemfSoc. 47, 2002 (192 5) which depends upon the addition of any organomet-allic compound to Michlers ketone, showed the presence of the organosodium compound, 'Color Test-l-l (ref. 2, Gilman and Swiss, 'J. Am. Chem.'Soc.-62, 1847 (1940)), which distinguishes between organolitliium or organosodium compounds and Grignard reagents by metalation of triphenylmethane, showed theapresence of the organosodium compound. The triphenylmethyl sodium that resulted from this latter test was carbonated on solid carbon dioxide and 'a'meltin'g point "sample oftri-phenylacetic acid ('M. P. 262-264 'C.) was obtained. To the reaction mixture containing disodiooctadiene was added an equimolar amount of magnesium chloride and the reaction mixture stirred in the ball mill reactor for 1 hour. At the end of this time Color Test I (ref. 1) was positive, showing the presence of an organometalli-c compound presumably the di-Grignard reagent, while Color Test II (ref. 2) was negative, indicating that the disodiooctadiene had been completely converted to the bischloromagnesiooctadiene. Carbonation of this reaction mixture on solid carbon dioxide gave a 70% yield of a mixture of 10- carbon atom d-ibasic acids.

What is claimed is:

1. The process which comprises preparing an unsaturated di-Grignard reagent by contacting an aliphatic conjugated diolefin with dispersed sodium metal, and in the presence of solid anhydrous magnesium chloride in an ether containing reaction medium, at a temperature between -40 C. and +40 0., thereby forming the corresponding di-Grignard derivatives of the unsaturated hydrocarbon dimers of said diolefin.

2. The process according to claim 1 in which the aliphatic conjugated diolefin is butadiene.

3. The process which comprises continuously agitating in an attrition reactor an aliphatic conjugated diolefin with dispersed sodium metal in a methyl ether reaction medium in the presence of from 0.1 to 10 wt. percent, based on the diolefin, of a polycyclic aromatic hydrocarbon and in the presence of solid anhydrous magnesium chloride while maintaining a temperature between +40 and --40 C., thereby forming the correspond-ing di-G-rignard derivatives of the unsaturated hydrocarbon dimers of said diolefin.

4. The process according to claim 3 in which the aliphatic conjugated diolefin is butadiene.

5. The process which comprises reacting in an attrition reactor an aliphatic conjugated diolefin with dispersed sodium metal in a methyl ether reaction medium in the presence of a small amount of a polycyclic aromatic hydrocarbon and in the presence of solid anhydrous magnesium chloride, at a temperature between 0 and 40 C., thereby forming the corresponding di-Gr-ignard derivatives of the unsaturated hydrocarbon dimers of said diolefin, and directly thereafter carbonating said derivatives thereby forming the aliphatic unsaturated dicarboxylic acids having two more carbon atoms than the said unsaturated hydrocarbon dimers.

6. The process according to that described in claim in which the conjugated diolefin is butadiene.

7. The process which comprises preparing an unsaturated di-Grignard reagent by reacting the disodio derivatives of the unsaturated hydrocarbon dimers of an aliphatic conjugated diolefin with solid anhydrous magnesium chloride in an ether containing reaction medium, at a temperature between 40 and +40 C., thereby forming the corresponding d-i-Grignard reagent of the unsaturated hyd-rocarbon dimers of said diolefin.

8. The process according to claim 7 in which the aliphatic conjugated diolefin is butadiene.

9. The process which comprises agitating in an attrition reactor .the disodio derivatives of the unsaturated hydro carbon dimers of an aliphatic conjugated diolefin with solid anhydrous magnesium chloride in a methyl ether reaction medium, thereby forming the corresponding di- Grignard derivatives of the unsaturated hydrocarbon dimers of said diolefin.

10. The process according to claim 9 in which the aliphatic conjugated diolefin is butadiene.

11. A composition of matter comprising at least one unsaturated di-Grignard derivative having the formula:

wherein R, R and R" represent substituents selected from the group consisting of hydrogen and alkyl radicals, R

represents an alkenyl radical, and m and n represent whole number integers selected from the group consisting of 0 to l, inclusive.

12. A composition of matter comprising bis-1,8-chloromagnesio-2,6-octadiene.

13. A composition of matter comprising bis-1,6-chloromagnesio-2,7-octadiene.

, 14. A composition of matter comprising bis-3,6-chloromagnesio-l,7-oetadiene.

15. A composition of matter comprising a mixture of bis-chloromagnesio-octad-ienes.

16. A process, as defined in claim 1, wherein the sodium reactant is a dispersion of sodium having an average particle size of less than about microns.

17. As a new composition, a reaction mixture, obtained from the process of claim 1, containing a di-Grignard derivative of the dimer of the diolefin.

1-8. As a new composition, a reaction mixture, obtained from the process of claim 1 in which butadiene is the diolefin reactant, containing bis-1,8-chloromagnesio- 2,6-octadiene, bis-1,6-chloromagnesio-2,7-octadiene, and

bis-3,6chloromagnesio-l,7-octadiene. 

1. THE PROCESS WHICH COMPRISES PREPARING AN UNSATURATED DI-GRIGNARD REAGENT BY CONTACTING AN ALIPHATIC CONJUGATED DIOLEFIN WITH DISPERSED SODIUM METAL, AND IN THE PRESENCE OF SOLID ANHYDROUS MAGNESIUM CHLORIDE IN AN ETHER CONTAINING REACTION MEDIUM, AT A TEMPERATURE BETWEEN -40*C. AND +40*C., THEREBY FORMING THE CORRESPONDING DI-GRIGNARD DERIVATIVES OF THE UNSATURATED HYDROCARBON DIMERS OF SAID DIOLEFIN. 